The game comes with 30 days of free playtime, but after that you’ll need a credit card to keep playing:

Notice:Included with your purchase of FINAL FANTASY XI is 30 days of free time. Additional monthly fees apply. The subscription for this game requires a valid credit card that supports Verified by Visa® or MasterCard SecureCode®.

For those customers that do not have a credit card that supports Verified by Visa® or MasterCard SecureCode®, Square Enix is able to assist you with creating an account. For additional information on this, please go here

For 50% off, this could be quite a bargain, if you’re looking to try out a new MMO without playing through the roof for it. The game was generally well received at the time of release, and could perhaps offer a “warm-up” of sorts for those of you excited for Final Fantasy XIV to come out.